CD44 Promotes Migration and Invasion of Docetaxel-Resistant Prostate Cancer Cells Likely via Induction of Hippo-Yap Signaling

Patients receiving docetaxel developed a drug resistance within a few months. We generated docetaxel-resistant PC/DX25 and DU/DX50 CRPC cells from PC-3 and DU-145 PCa cells, respectively. We investigated the mechanism behind why PC/DX25 and DU/DX50 cells exhibited higher migration and invasion ability. Transwell assays were used to measure the migration and invasion of PCa cell. Fluorescence activated cell sorter (FACS) analysis was used to determine the population of cancer stem cell (CSC)-like cell. Micro-Western Array (MWA) was used to study the changes of the protein profile. FACS analysis revealed that PC/DX25 cells and DU/DX50 cells contain higher CD44+ population. MWA and Western blotting assay revealed that protein expression of CD44, YAP, CYR61, CTGF, phospho-ERK1/2 T202/Y204, ERK and vimentin was elevated in PC/DX25 cells. Knockdown of CD44 or YAP suppressed migration and invasion of PC/DX25 and DU/DX50 cells. Knockdown of CD44 decreased expression of YAP, CTGF and CYR61 but increased phosphorylation of S127 on YAP. CD44 knockdown also suppressed protein level of AKT, phospho-AKT T308, phospho-ERK1/2 T202/Y204 and vimentin. CD44 promotes migration and invasion of docetaxel-resistant PCa cells probably via induction of Hippo-Yap signaling pathway and CD44/YAP pathway may be a therapeutic target for docetaxel-resistant PCa.